Invalid Credentials, despite being able to log on less than an hour ago [closed]

If you are 100 % sure that it is the correct password, (which almost 85 % of the time your typing the password wrong and this happens frequently with new accounts that people make with new passwords and they mistake it for other passwords they use), you have to face the scenario of you being hacked. This happened to me just a week ago, and you can reset your password on the Minecraft Launcher if you still have the email. If not, then you can contact Minecraft customer support and ask for help.

When are you getting this error message?

If it's while you're attempting to join a server, all you need to do is close the game and launcher, and run them again.

If it's while you're trying to log into the launcher, and/or while you're trying to log in to minecraft.net, then you need to reset your password.

If your account has been compromised, and you haven't told your password to anybody, then it's possible that you have a security vulnerability on your computer - you should investigate accordingly.